1. Field of the Invention
This invention relates to a method for manufacturing a thin metal band which is capable of readily and arbitrarily varying the width of the band, and a thin metal band manufactured according to this method.
2. Explanation of the Prior Art
A winding core for use in a static induction machine, such as a transformer, is manufactured by coiling a silicon steel band. Such a winding core is divided beforehand into two parts, since it is not possible to wind a coil wire on an original intact form of winding core. The two core parts are assembled into one unit after these two core parts have been individually wound by a coil wire. However, a transformer equipped with such a winding core experiences the degeneration of the magnetic properties due to the presence of the divided parts of the winding core unit. A transformer having a substantially circular cross section is known as an improved transformer. This transformer is obtained by placing a split bobbin around the outer periphery of the winding core and winding a coil wire around the bobbin on the winding core, while turning the bobbin unit. Therefore, it is not necessary to divide the winding core into two units. This type of transformer can improve the magnetic properties.
The winding core having a substantially circular cross section is obtained by winding a thin metal band having a first section of a gradually increasing width, a central section of a uniform width merging with the first section and a second section of a gradually decreasing width merging with the central section. The thin metal band of such a configuration is formed by rolling a metal sheet into a thin metal band of a uniform width at a rolling step and cutting the thin metal band at a cutting step into a desired configuration. However, this step requires an additional cutting step for obtaining the first and second sections, resulting in a lower yield.
Recently, a winding core has been proposed which is formed of an amorphous, magnetic thin alloy band. This alloy band is formed by flowing a molten metal-metalloid alloy onto a rotating cooling roll or a running cooling band to permit it to be quenched. The thin metal band has excellent magnetic properties with a lower core loss.